WO2011046317A2 - 다중-셀 협력 통신 모드 및 단일-셀 mimo 통신 모드 간의 모드 스위칭 방법 및 장치 - Google Patents
다중-셀 협력 통신 모드 및 단일-셀 mimo 통신 모드 간의 모드 스위칭 방법 및 장치 Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
- H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0636—Feedback format
- H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
- H04B7/0689—Hybrid systems, i.e. switching and simultaneous transmission using different transmission schemes, at least one of them being a diversity transmission scheme
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/02—Terminal devices
- H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B7/0478—Special codebook structures directed to feedback optimisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B7/0482—Adaptive codebooks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0621—Feedback content
- H04B7/0632—Channel quality parameters, e.g. channel quality indicator [CQI]
Definitions
- the following description relates to a wireless communication system, and more particularly, to a method and apparatus for mode switching between a multi-cell cooperative communication mode and a single-cell MIMO communication mode.
- Multi-Input Multi-Output is a technology that improves the transmission and reception efficiency of data by using multiple transmission antennas and multiple reception antennas, instead of using one transmission antenna and one reception antenna.
- MIMO Multi-Input Multi-Output
- the receiving side receives data through a single antenna path, but using multiple antennas, the receiving end receives data through multiple paths. Therefore, the data transmission speed and the transmission amount can be improved, and the coverage can be increased.
- Single-cell MIMO operation is a single user-MIMO (SU-MIMO) scheme in which one terminal receives a downlink signal in one cell and two or more terminals are downlinked in one cell. It can be divided into a multi-user-MIMO (MU-MIMO) scheme for receiving a link signal.
- SU-MIMO single user-MIMO
- MU-MIMO multi-user-MIMO
- CoMP coordinated multi-point
- the CoMP scheme may be divided into, for example, a Joint Processing (JP) scheme in which downlink data to be transmitted to a specific UE is shared among all CoMP cooperative cells, and a Coordinated BeamForming (CBF) scheme in which downlink data exists in only one cell.
- JP Joint Processing
- CBF Coordinated BeamForming
- JT Joint Transmission
- CSL Cooperative SiLencing
- cooperative cells that do not transmit a signal to the terminal may reduce interference between cells by determining a beamforming matrix of the terminal that receives a signal from the terminal so that a small amount of interference is applied to the terminal.
- Multi-cell CoMP operation can be viewed as an extension of single-cell MIMO operation.
- the multi-cell CoMP operation may be regarded as a virtual MIMO system by combining a plurality of spatially separated base stations (or cells) into a group.
- the communication schemes of the multi-cell CoMP operation are closely related to the communication schemes of the single-cell MIMO operation.
- a method of dynamically switching a communication mode generating and transmitting first feedback information according to a first communication mode, the first communication mode in the Switching to a second communication mode interworking with a first communication mode, and generating and transmitting second feedback information in accordance with the second communication mode, wherein the first communication mode is a multi-cell cooperative multipoint.
- the second communication mode is the other one of the CoMP communication mode or the single-cell MIMO mode other than the first communication mode
- the switching step may be performed without signaling from the base station.
- the linkage between the first communication mode and the second communication mode is set between a CoMP communication method supporting high rank transmission and a single-cell MIMO communication method supporting high rank transmission, and supporting low rank transmission. It may be established between the CoMP communication scheme and the single-cell MIMO communication scheme supporting low rank transmission.
- the CoMP communication scheme supporting the high rank transmission and the single-cell MIMO communication scheme supporting the high rank transmission are CoMP JT (Joint Transmission) scheme and single-cell single user-MIMO (SU-MIMO) scheme, respectively.
- the CoMP communication scheme supporting the low rank transmission and the single-cell MIMO communication scheme supporting the low rank transmission are CoMP Coordinated BeamForming (CBF) scheme and single-cell multi-user-MIMO (MU-MIMO) scheme, respectively. Can be.
- first feedback information and the second feedback information may be generated using the same feedback codebook.
- the first feedback information is generated using a first feedback codebook
- the second feedback information is generated using a second feedback codebook
- one of the first feedback codebook and the second feedback codebook is the other one. It can consist of a subset of.
- a feedback codebook used in the single-cell MIMO communication mode may be configured as a subset of the feedback codebook used in the CoMP communication mode.
- the feedback information in the single-cell MIMO communication mode may be a subset of the feedback information in the CoMP communication mode.
- the first feedback information and the second feedback information are converted into a unitary matrix. Can be generated using the configured feedback codebook.
- the first feedback information and the second feedback information may be non-unitary. It can be generated using a matrix of feedback codebooks.
- the first feedback information and the second feedback information may include the first feedback information when the linkage between the first communication mode and the second communication mode is set between a CoMP CBF scheme and a single-cell MU-MIMO scheme.
- the interworking of the communication mode and the second communication mode may be generated using a feedback codebook having a higher granularity than when the communication mode and the second communication mode are set between the CoMP JT method and the single-cell SU-MIMO method.
- the higher precision feedback codebook may be composed of a larger size feedback codebook, hierarchical codebook, or adaptive codebook.
- the first feedback information and the second feedback information may be generated based on the same hypothesis for calculating the channel quality indicator (CQI).
- CQI channel quality indicator
- the same MIMO transmission scheme may be used in the first communication mode and the second communication mode.
- a terminal for dynamically switching a communication mode a receiving module for receiving a downlink signal from a base station, a transmission module for transmitting an uplink signal to the base station; And a processor controlling the terminal including the receiving module and the transmitting module, wherein the processor generates first feedback information according to a first communication mode and generates second feedback information according to a second communication mode.
- the first module transmits the first feedback information when operating in the first communication mode and the second feedback information when operating in the second communication mode, and transmits the first communication mode and the through the transmission module. And switch between a second communication mode, the first communication mode and the second communication mode interlocked.
- the first communication mode is one of a multi-cell cooperative multipoint (CoMP) communication mode or a single-cell multiple input / output (MIMO) communication mode
- the second communication mode is the CoMP communication mode or the single- mode.
- the other one of the cell MIMO modes other than the first communication mode, and switching between the first communication mode and the second communication mode may be performed without signaling from the base station.
- mode switching between the multi-cell cooperative communication mode and the single-cell MIMO communication mode can be performed dynamically and efficiently.
- FIG. 1 is a diagram conceptually illustrating CoMP operation of an intra eNB and an inter eNB. Referring to FIG.
- FIG. 2 is a block diagram showing the structure of a transmitter having multiple antennas.
- 3 is a diagram illustrating a structure of a type 1 radio frame.
- 5 is an exemplary diagram illustrating an example of a resource grid for one downlink slot.
- FIG. 6 is a diagram illustrating a structure of a downlink subframe.
- FIG. 7 is a diagram illustrating a structure of an uplink subframe.
- FIG. 8 is a configuration diagram of a wireless communication system having multiple antennas.
- 9 is a diagram illustrating a basic concept of codebook based precoding.
- FIG. 10 is a diagram for conceptually explaining an interlocking and switching operation between a CoMP communication scheme and a single-cell MIMO communication scheme.
- FIG. 11 is a flowchart illustrating a dynamic switching method between a CoMP communication mode and a single-cell MIMO communication mode according to an embodiment of the present invention.
- FIG. 12 is a diagram showing the configuration of a preferred embodiment of a terminal device according to the present invention.
- each component or feature may be considered to be optional unless otherwise stated.
- Each component or feature may be embodied in a form that is not combined with other components or features.
- some components and / or features may be combined to form an embodiment of the present invention.
- the order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.
- the base station has a meaning as a terminal node of the network that directly communicates with the terminal.
- the specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.
- a 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point (AP), and the like.
- the term base station may be used as a concept including a cell or a sector.
- a serving base station may be referred to as a serving cell
- a cooperative base station may also be referred to as a cooperative cell.
- terminal may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), a subscriber station (SS), and the like.
- Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802 system, 3GPP system, 3GPP LTE and LTE-Advanced (LTE-A) system and 3GPP2 system. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.
- CDMA code division multiple access
- FDMA frequency division multiple access
- TDMA time division multiple access
- OFDMA orthogonal frequency division multiple access
- SC-FDMA single carrier frequency division multiple access
- CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000.
- TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE).
- GSM Global System for Mobile communications
- GPRS General Packet Radio Service
- EDGE Enhanced Data Rates for GSM Evolution
- OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA).
- UTRA is part of the Universal Mobile Telecommunications System (UMTS).
- 3rd Generation Partnership Project (3GPP) long term evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink.
- LTE-A Advanced
- WiMAX can be described by the IEEE 802.16e standard (WirelessMAN-OFDMA Reference System) and the advanced IEEE 802.16m standard (WirelessMAN-OFDMA Advanced system). For clarity, the following description focuses on the 3GPP LTE and LTE-A standards, but the technical spirit of the present invention is not limited thereto.
- intra base stations 110 and 120 and inter base stations 130 exist in a multi-cell environment.
- an intra base station consists of several cells (or sectors).
- Cells belonging to a base station to which a specific terminal belongs are in an intra base station (110, 120) relationship with the specific terminal. That is, cells sharing the same base station as its own cell to which the terminal belongs are cells corresponding to the intra base stations 110 and 120 and cells belonging to other base stations are cells corresponding to the inter base station 130.
- cells based on the same base station as a specific terminal ie, an intra base station
- provide information for example, data and channel state information (CSI)
- CSI channel state information
- a single-cell MIMO user 150 within a single-cell communicates with one serving base station in one cell (cell A, cell B, cell D, or cell E) and at a cell boundary.
- the located multi-cell MIMO user 160 may communicate with multiple serving base stations in multiple cells (cell A and cell B, or cell B and cell C and cell D).
- the CoMP system is a system for improving throughput of users at cell boundaries by applying improved MIMO transmission in a multi-cell environment.
- Application of the CoMP system can reduce inter-cell interference in a multi-cell environment.
- the CoMP scheme may be divided into, for example, a Joint Processing (JP) scheme in which downlink data to be transmitted to a specific UE is shared among all CoMP cooperative cells, and a Coordinated BeamForming (CBF) scheme in which downlink data exists in only one cell.
- JP Joint Processing
- CBF Coordinated BeamForming
- JT Joint Transmission
- CSL Cooperative SiLencing
- cooperative cells that do not transmit a signal to the terminal may reduce interference between cells by determining a beamforming matrix of the terminal that receives a signal from the terminal so that a small amount of interference is applied to the terminal.
- the terminal can be jointly supported data from a multi-cell base station.
- each base station can improve the performance of the system by simultaneously supporting one or more terminals using the same radio frequency resource (Same Radio Frequency Resource).
- the base station may perform a space division multiple access (SDMA) method based on channel state information between the base station and the terminal.
- SDMA space division multiple access
- a serving base station and one or more cooperating base stations are connected to a scheduler through a backbone network.
- the scheduler may operate by receiving feedback of channel information about channel states between respective terminals and the cooperative base stations measured by each base station through the backbone network.
- the scheduler may schedule information for collaborative MIMO operation for the serving base station and one or more cooperating base stations. That is, the scheduler may directly give an indication of the cooperative MIMO operation to each base station.
- the CoMP system may be referred to as operating as a virtual MIMO system by combining a plurality of adjacent cells into a group, and basically, a communication technique of a MIMO system using multiple antennas may be applied.
- the operation of the MIMO system will be described in detail later.
- FIG. 2 is a block diagram showing the structure of a transmitter having multiple antennas.
- the transmitter 200 includes an encoder 210-1, ..., 210-K, a modulation mapper 220-1, ..., 220-K, and a layer mapper.
- the transmitter 200 includes Nt transmit antennas 270-1,..., 270 -Nt.
- the encoders 210-1, ..., 210-K encode the input data according to a predetermined coding scheme to form coded data.
- the modulation mapper 220-1, ..., 220-K maps the coded data to modulation symbols representing positions on signal constellations.
- the modulation scheme is not limited and may be m-Phase Shift Keying (m-PSK) or m-Quadrature Amplitude Modulation (m-QAM).
- m-PSK may be BPSK, QPSK or 8-PSK.
- m-QAM may be 16-QAM, 64-QAM or 256-QAM.
- the layer mapper 230 defines a layer of modulation symbols so that the precoder 240 can distribute antenna-specific symbols to the path of each antenna.
- the layer is defined as an information path input to the precoder 240.
- the information path before the precoder 240 may be referred to as a virtual antenna or layer.
- the precoder 240 outputs antenna specific symbols by processing the modulation symbols in a MIMO scheme according to the multiple transmit antennas 270-1,..., 270 -Nt.
- the precoder 240 distributes the antenna specific symbol to the resource element mappers 250-1,..., 250 -K of the path of the corresponding antenna.
- Each information path sent by the precoder 240 to one antenna is called a stream. This may be referred to as a physical antenna.
- the resource element mapper 250-1,..., 250 -K allocates an antenna specific symbol to an appropriate resource element and multiplexes it according to a user.
- the OFDM signal generators 260-1,..., 260 -K output an OFDM symbol by modulating the antenna specific symbol by the OFDM scheme.
- the OFDM signal generators 260-1,..., 260 -K may perform an inverse fast fourier transform (IFFT) on an antenna specific symbol, and a cyclic prefix (CP) is applied to the time domain symbol on which the IFFT is performed. ) Can be inserted.
- IFFT inverse fast fourier transform
- CP cyclic prefix
- the CP is a signal inserted in a guard interval to remove inter-symbol interference due to multiple paths in the OFDM transmission scheme.
- the OFDM symbol is transmitted through each transmit antenna 270-1,..., 270 -Nt.
- uplink / downlink data packet transmission is performed in subframe units, and one subframe is defined as a predetermined time interval including a plurality of OFDM symbols.
- the 3GPP LTE standard supports a type 1 radio frame structure applicable to frequency division duplex (FDD) and a type 2 radio frame structure applicable to time division duplex (TDD).
- the downlink radio frame consists of 10 subframes, and one subframe consists of two slots.
- the time it takes for one subframe to be transmitted is called a transmission time interval (TTI).
- TTI transmission time interval
- one subframe may have a length of 1 ms and one slot may have a length of 0.5 ms.
- One slot includes a plurality of OFDM symbols in the time domain and includes a plurality of resource blocks (RBs) in the frequency domain.
- the number of OFDM symbols included in one slot may vary depending on the configuration of the CP.
- CP has an extended CP (normal CP) and a normal CP (normal CP).
- normal CP normal CP
- the number of OFDM symbols included in one slot may be seven.
- the OFDM symbol is configured by an extended CP, since the length of one OFDM symbol is increased, the number of OFDM symbols included in one slot is smaller than that of the normal CP.
- the number of OFDM symbols included in one slot may be six. If the channel state is unstable, such as when the terminal moves at a high speed, an extended CP may be used to further reduce intersymbol interference.
- one subframe includes 14 OFDM symbols.
- the first two or three OFDM symbols of each subframe may be allocated to a physical downlink control channel (PDCCH), and the remaining OFDM symbols may be allocated to a physical downlink shared channel (PDSCH).
- PDCCH physical downlink control channel
- PDSCH physical downlink shared channel
- the type 2 radio frame consists of two half frames, and each half frame consists of five subframes. Subframes may be classified into a general subframe and a special subframe.
- the special subframe is a subframe including three fields of a downlink pilot time slot (DwPTS), a gap period (GP), and an uplink pilot time slot (UpPTS). The length of these three fields can be set individually, but the total length of the three fields must be 1 ms.
- One subframe consists of two slots. That is, regardless of the type of radio frame, one subframe consists of two slots.
- the structure of the radio frame is only an example, and the number of subframes included in the radio frame or the number of slots included in the subframe and the number of symbols included in the slot may be variously changed.
- the downlink slot includes a plurality of OFDM symbols in the time domain and includes a plurality of resource blocks (RBs) in the frequency domain.
- RBs resource blocks
- one downlink slot includes 7 OFDM symbols and one resource block includes 12 subcarriers, but is not limited thereto.
- Each element on the resource grid is called a resource element (RE).
- the resource element a (k, l) becomes a resource element located in the k-th subcarrier and the l-th OFDM symbol.
- one resource block includes 12x7 resource elements (in the case of an extended CP, 12x6 resource elements). Since the interval of each subcarrier is 15 kHz, one resource block includes about 180 kHz in the frequency domain.
- N DL is the number of resource blocks included in the downlink slot. The value of N DL may be determined according to a downlink transmission bandwidth set by scheduling of the base station.
- FIG. 6 is a diagram illustrating a structure of a downlink subframe.
- Up to three (one, two, or three) OFDM symbols in front of the first slot in one subframe correspond to a control region to which a control channel is allocated.
- the remaining OFDM symbols correspond to data regions to which a physical downlink shared channel (PDSCH) is allocated.
- the basic unit of transmission is one subframe. That is, PDCCH and PDSCH are allocated over two slots.
- Downlink control channels used in the 3GPP LTE system include, for example, a Physical Control Format Indicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH), and a Physical HARQ Indicator Channel.
- PCFICH Physical Control Format Indicator Channel
- PDCCH Physical Downlink Control Channel
- PHICH Physical Hybrid automatic repeat request Indicator Channel
- the PCFICH is transmitted in the first OFDM symbol of a subframe and includes information on the number of OFDM symbols used for control channel transmission in the subframe.
- the PHICH includes a HARQ ACK / NACK signal as a response of uplink transmission.
- Control information transmitted through the PDCCH is referred to as downlink control information (DCI).
- DCI includes uplink or downlink scheduling information or an uplink transmit power control command for a certain terminal group.
- the PDCCH is a resource allocation and transmission format of the downlink shared channel (DL-SCH), resource allocation information of the uplink shared channel (UL-SCH), paging information of the paging channel (PCH), system information on the DL-SCH, on the PDSCH Resource allocation of upper layer control messages such as random access responses transmitted to the network, a set of transmit power control commands for individual terminals in an arbitrary terminal group, transmission power control information, and activation of voice over IP (VoIP) And the like.
- a plurality of PDCCHs may be transmitted in the control region.
- the terminal may monitor the plurality of PDCCHs.
- the PDCCH is transmitted in a combination of one or more consecutive Control Channel Elements (CCEs).
- CCEs Control Channel Elements
- the CCE is a logical allocation unit used to provide a PDCCH at a coding rate based on the state of a radio channel.
- the CCE corresponds to a plurality of resource element groups.
- the format of the PDCCH and the number of available bits are determined according to the correlation between the number of CCEs and the coding rate provided by the CCEs.
- the base station determines the PDCCH format according to the DCI transmitted to the terminal, and adds a cyclic redundancy check (CRC) to the control information.
- the CRC is masked with an identifier called a Radio Network Temporary Identifier (RNTI) according to the owner or purpose of the PDCCH.
- RNTI Radio Network Temporary Identifier
- the cell-RNTI (C-RNTI) identifier of the terminal may be masked to the CRC.
- a paging indicator identifier P-RNTI
- the PDCCH is for system information (more specifically, system information block (SIB))
- SI-RNTI system information RNTI
- RA-RNTI Random Access-RNTI
- RA-RNTI may be masked to the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the terminal.
- the uplink subframe may be divided into a control region and a data region in the frequency domain.
- a physical uplink control channel (PUCCH) including uplink control information is allocated to the control region.
- PUSCH physical uplink shared channel
- PUCCH has three main uses: transmission of ACK / NACK for PDSCH, transmission of Channel Quality Indicator (CQI) for frequency domain scheduling of PDSCH, and request for PUSCH transmission resource (scheduling request). to be.
- the CQI information bit may include one or more fields.
- a CQI field indicating a CQI index for determining a Modulation and Coding Scheme (MCS), a Precoding Matrix Indicator (PMI) field indicating an index of a precoding matrix on a codebook, and a RI (Rank Indicator) field indicating a rank Etc. may be included in the CQI information bits.
- one UE does not simultaneously transmit a PUCCH and a PUSCH.
- PUCCH for one UE is allocated to an RB pair in a subframe.
- Resource blocks belonging to a resource block pair occupy different subcarriers for two slots. This is called a resource block pair allocated to the PUCCH is frequency-hopped at the slot boundary.
- FIG. 8 is a configuration diagram of a wireless communication system having multiple antennas.
- the theoretical ratio is proportional to the number of antennas, unlike when the transmitter or receiver uses only a plurality of antennas.
- Channel transmission capacity is increased. Therefore, the transmission rate can be improved and the frequency efficiency can be significantly improved.
- the transmission rate can theoretically increase as the rate of increase rate R i multiplied by the maximum transmission rate R o when using a single antenna.
- a transmission rate four times higher than a single antenna system may be theoretically obtained. Since the theoretical capacity increase of multi-antenna systems was proved in the mid 90's, various techniques to actively lead to the actual data rate improvement have been actively studied. In addition, some technologies are already being reflected in various wireless communication standards such as 3G mobile communication and next generation WLAN.
- the research trends related to multi-antennas to date include the study of information theory aspects related to the calculation of multi-antenna communication capacity in various channel environments and multi-access environments, the study of wireless channel measurement and model derivation of multi-antenna systems, improvement of transmission reliability, and improvement of transmission rate. Research is being actively conducted from various viewpoints, such as research on space-time signal processing technology.
- the transmission signal when there are N T transmit antennas, the maximum information that can be transmitted is N T.
- the transmission information may be expressed as follows.
- Each transmission information The transmit power may be different.
- Each transmit power In this case, the transmission information whose transmission power is adjusted may be expressed as follows.
- Weighting matrix N T transmitted signals actually applied by applying Consider the case where. Weighting matrix Plays a role in properly distributing transmission information to each antenna according to a transmission channel situation.
- Vector It can be expressed as follows.
- Receive signal is received signal of each antenna when there are N R receive antennas Can be expressed as a vector as
- channels may be divided according to transmit / receive antenna indexes. From the transmit antenna j to the channel through the receive antenna i It is indicated by. Note that in the order of the index, the receiving antenna index is first, and the index of the transmitting antenna is later.
- FIG. 8 (b) shows a channel from N T transmit antennas to receive antenna i .
- the channels may be bundled and displayed in vector and matrix form.
- a channel arriving from the total N T transmit antennas to the receive antenna i may be represented as follows.
- AWGN Additive White Gaussian Noise
- the received signal may be expressed as follows through the above-described mathematical modeling.
- the channel matrix indicating the channel state The number of rows and columns of is determined by the number of transmit and receive antennas.
- Channel matrix The number of rows is equal to the number of receive antennas N R
- the number of columns is equal to the number of transmit antennas N T. That is, the channel matrix The matrix is N R ⁇ N T.
- the rank of a matrix is defined as the minimum number of rows or columns that are independent of each other. Thus, the rank of the matrix cannot be greater than the number of rows or columns.
- Channel matrix Rank of ( ) Is limited to
- rank may be defined as the number of nonzero eigenvalues when the matrix is eigenvalue decomposition.
- another definition of rank may be defined as the number of nonzero singular values when singular value decomposition is performed. Therefore, the physical meaning of rank in the channel matrix is the maximum number that can send different information in a given channel.
- 'rank' for MIMO transmission refers to the number of paths that can independently transmit signals at specific time points and specific frequency resources, and 'number of layers' denotes each path. It indicates the number of signal streams transmitted through the system. In general, since the transmitting end transmits the number of layers corresponding to the number of ranks used for signal transmission, unless otherwise specified, the rank has the same meaning as the number of layers.
- MIMO transmission schemes transmission modes
- Multiple antenna transmit / receive schemes used for the operation of MIMO systems include frequency switched transmit diversity (FST), Space Frequency Block Code (SFBC), Space Time Block Code (STBC), Cyclic Delay Diversity (CDD), TSTD (time switched transmit diversity) may be used.
- FST frequency switched transmit diversity
- SFBC Space Frequency Block Code
- STBC Space Time Block Code
- CDD Cyclic Delay Diversity
- TSTD time switched transmit diversity
- SM spatial multiplexing
- GCDD Generalized Cyclic Delay Diversity
- S-VAP Selective Virtual Antenna Permutation
- FSTD is a method of obtaining diversity gain by allocating subcarriers having different frequencies for each signal transmitted to each of the multiple antennas.
- SFBC is a technique that efficiently applies selectivity in the spatial domain and frequency domain to secure both diversity gain and multi-user scheduling gain in the corresponding dimension.
- STBC is a technique for applying selectivity in the space domain and the time domain.
- CDD is a technique of obtaining diversity gain by using path delay between transmission antennas.
- TSTD is a technique of time-dividing a signal transmitted through multiple antennas.
- Spatial multiplexing is a technique to increase the data rate by transmitting different data for each antenna.
- GCDD is a technique for applying selectivity in the time domain and the frequency domain.
- S-VAP is a technique using a single precoding matrix.
- Multi-codeword (MCW) S which mixes multiple codewords between antennas in spatial diversity or spatial multiplexing, and Single Codeword (SCW) S using single codeword. There is a VAP.
- Various types of scheduling signaling may be used according to various MIMO transmission schemes (MIMO transmission mode) as described above. That is, the scheduling signaling may have a different form for various MIMO transmission modes, and the terminal may determine the MIMO transmission mode according to the scheduling signaling.
- MIMO transmission mode MIMO transmission schemes
- the receiving end transmits feedback information about the channel state to the transmitting end, thereby allowing the transmitting end to grasp the channel state, thereby improving the performance of the wireless communication system.
- the closed loop MIMO system uses a precoding scheme in which a transmitter minimizes the influence of a channel by performing a predetermined process on transmission data using feedback information about a channel environment transmitted from a receiver.
- Precoding schemes include a codebook based precoding scheme and a precoding scheme for quantizing and feeding back channel information.
- FIG. 9 is a diagram illustrating a basic concept of codebook based precoding.
- the transmitting and receiving end shares codebook information including a predetermined number of precoding matrices according to a transmission rank, the number of antennas, and the like.
- the receiving side measures the channel state through the received signal and feeds back the preferred precoding matrix information (precoding matrix index) to the transmitting side based on the above-described codebook information.
- the receiving end transmits the precoding matrix information preferred for the transmitting end for each codeword, but is not limited thereto.
- the transmitter receiving feedback information from the receiver may select a specific precoding matrix from the codebook based on the received information.
- the transmitter that selects the precoding matrix performs precoding by multiplying the number of layer signals corresponding to the transmission rank by the selected precoding matrix, and transmits the precoded transmission signal through a plurality of antennas.
- the receiving end receiving the signal precoded and transmitted by the transmitting end may restore the received signal by performing reverse processing of the precoding performed by the transmitting end.
- the inverse processing of the precoding described above is a Hermit of the precoding matrix P used for the precoding of the transmitter. (Hermit) matrix (P H ) can be made by multiplying the received signal.
- a method of feeding back channel information to a transmitting station (base station) by a receiving end (terminal) in a multi-cell environment may be applied using the above codebook based precoding scheme.
- a precoding matrix index (PMI) of a virtual multi-antenna channel which is formed between cooperating base stations and terminals belonging to a cooperating group, each stream Signal-to-Noise Ratio (SNR) (or Signal-to-Interference plus Noise Ratio (SINR)), the number of independent data that can be transmitted (i.e., rank) Information such as information) needs to be fed back from the terminal to the base station.
- SNR Signal-to-Noise Ratio
- SINR Signal-to-Interference plus Noise Ratio
- the UE As a method of feeding back channel information necessary for CoMP operation, the UE extends the channel information feedback scheme used in conventional single-cell MIMO communication, that is, the UE transmits PMI, signal-to-noise ratio, and rank of a channel with one base station.
- a method of quantizing channel information with each cooperating base station using a single codebook that uses a fixed number of bits to represent each channel, and then feeding back them to the base station may be considered.
- the neighboring base stations may use the feedback information to determine the cooperative unit and the cooperative communication scheme and transmit the result to the terminals.
- the terminal uses the information transmitted by the base station to provide channel information with each base station that cooperates using a single codebook that uses a fixed number of bits for indicating the PMI, signal-to-noise ratio, and rank of the channel with one base station. Quantization, and if necessary, the phase difference information between the PMI of the channel with each base station may be further quantized and fed back to the base station. Accordingly, the base station may perform inter-cell cooperative communication using information fed back by each terminal.
- the base station transmits a reference signal or a pilot signal, and the terminal estimates a channel using the reference signal.
- the channel information on the selected subband may be quantized and fed back to the base station using a single level quantization bit.
- the base station may perform cooperative transmission mode determination and user scheduling using information fed back by the terminal and transmit data to the selected user.
- the terminal may transmit acknowledgment (ACK / NACK) information for data transmission from the base station.
- the multi-cell CoMP communication technique may be divided into a joint processing (JP) method and a coordinated beamforming (CBF) method, and there are a JT (Joint Transmission) method and a Cooperative SiLencing (CSL) method.
- JP joint processing
- CBF coordinated beamforming
- CSL Cooperative SiLencing
- the single-cell MIMO scheme can be divided into a single user-MIMO (SU-MIMO) scheme and a multi-user-MIMO (MU-MIMO) scheme.
- the communication methods of the multi-cell CoMP operation are the communication methods of the single-cell MIMO operation.
- the present invention proposes a mode switching method between a multi-cell CoMP communication mode and a single-cell MIMO communication mode. Specifically, it looks at the appropriate communication schemes (ie, interworking) to which dynamic mode switching can be applied between the multi-cell CoMP communication mode and the single-cell MIMO communication mode, and dynamically switches between the interworking communication methods. It describes how to do this and detailed suggestions for supporting it.
- the CoMP communication scheme and the single-cell MIMO communication scheme may be interworked based on the rank.
- the rank refers to the number of data layers simultaneously transmitted to one UE at a specific time point and a specific frequency resource.
- these two communication schemes have a common point in that they generally perform high rank transmission. More specifically, in the case of CoMP JT scheme, since two or more cells participate in transmission for one UE, a high rank transmission is likely. In addition, in the case of the single-cell SU-MIMO scheme, it is highly likely that one UE uses a high rank transmission using all spatial resources of one cell. Therefore, based on a common point in which high rank transmission is made, it is possible to consider the interworking of the CoMP JT scheme and the single-cell SU-MIMO scheme.
- Dynamic switching means switching from one scheme to another without separate signaling from the base station. That is, no separate signaling may be required in switching from CoMP JT scheme to single-cell SU-MIMO scheme or from single-cell SU-MIMO scheme to CoMP JT scheme. Dynamic switching from the CoMP JT method to the single-cell SU-MIMO method may be expressed as falling-back without a separate signal from the CoMP JT method to the single-cell SU-MIMO method.
- the fall-back from the CoMP JT method to the single-cell SU-MIMO method means that a signal is transmitted to one UE from two or more cells according to the CoMP JT method, and then only one cell transmits a signal to the UE and the other cell. Stops signal transmission to the corresponding UE, which may be referred to as operating in a single-cell SU-MIMO scheme.
- the CBF method of the CoMP communication method and the MU-MIMO method of the single-cell MIMO communication method since these two communication methods generally have a common point in performing low rank transmission, these two communication methods are common.
- the interworking of the schemes can be considered. More specifically, in the case of the CoMP CBF scheme, it is generally difficult to use a high rank in that a signal for one terminal is transmitted only from one base station, and a CoMP operation is mainly performed for the terminal at a cell boundary.
- the cooperative cell should determine the beam direction in a direction not used by the target terminal of the CoMP operation. It can also be narrowed. Therefore, the CoMP CBF scheme generally performs low rank transmission.
- the rank of each terminal is generally set to a low value because two or more terminals share a spatial resource of one cell to receive a signal.
- the two communication schemes can be interworked with each other so that dynamic switching can be easily performed. That is, no separate signaling may be required in switching from CoMP CBF scheme to single-cell MU-MIMO scheme or from single-cell MU-MIMO scheme to CoMP CBF scheme.
- the dynamic switching from the CoMP CBF scheme to the single-cell MU-MIMO scheme may be expressed as falling back without a separate signal from the CoMP CBF scheme to the single-cell MU-MIMO scheme.
- the fall-back from the CoMP CBF scheme to the single-cell MU-MIMO scheme means, for example, that the beam of the cell B is transmitted by the cell A in cooperation with the cell B in performing the MIMO transmission for the plurality of terminals in the cell A. It is operated so as not to be formed in the direction of the plurality of terminals receiving signals from (ie, CoMP CBF method operation), and means that MIMO transmission to a plurality of terminals by cell A alone without cell B's beamforming cooperation. This can be said to operate as a single-cell MU-MIMO.
- the CSL method of the CoMP communication method may be linked with CoMP JT belonging to the CoMP JP method, and switching between these communication methods may be performed dynamically.
- switching between one of the CoMP JT scheme or the single-cell SU-MIMO scheme and one of the CoMP CBF scheme or the single-cell MU-MIMO scheme may also be performed dynamically.
- the switching between the CoMP communication scheme and the single-cell MIMO communication scheme according to the above description may be represented as shown in FIG. 10.
- switching between the CoMP communication method and the single-cell MIMO communication method other than the interworking between the CoMP JT method and the single-cell SU-MIMO method and the interworking between the CoMP CBF method and the single-cell MU-MIMO method is dynamically performed. Suggest not to be performed. That is, switching between CoMP and single-cell MIMO communication schemes other than the interworking of the aforementioned CoMP and single-cell MIMO communication schemes may be switched through higher layer signals (eg, RRC signaling).
- higher layer signals eg, RRC signaling
- a higher layer signal indicating this is transmitted from the base station to the terminal and the terminal according to the corresponding signal. It can be operated semi-statically in either way.
- the interworking between the CoMP communication method and the single-cell MIMO communication method indicates that switching can be performed dynamically without additional signaling.
- the CoMP communication method and the single-cell MIMO communication method are set to have a common point in CQI transmission and feedback codebook use.
- the terminal apply the same hypothesis when calculating the channel quality indicator (CQI) and / or rank indicator (RI).
- CQI channel quality indicator
- RI rank indicator
- Applying the same hypothesis means following the same setup and method for CQI and / or RI calculation and transmission.
- Hypotheses for CQI and RI calculations may include periodic / aperiodic transmissions, transmission periods in the case of periodic transmissions, frequency bands subject to CQI calculations, MIMO transmission schemes, and the relationship between CQI and RI.
- the same hypothesis may be applied to communication schemes interworking with respect to.
- the CQI is calculated based on channel quality such as a signal-to-noise ratio (SNR), and may provide information about a link adaptive parameter that can be supported by the terminal for a given time.
- SNR signal-to-noise ratio
- CQI is a wideband feedback scheme in which one CQI value is fed back over the entire system band, and after the UE estimates channel quality of each subband, a plurality of high quality subbands are selected and a plurality of selected UE-selected sub-band feedback scheme that feeds back average CQI values for subbands; higher layer configuration subband feedback that feeds back individual CQIs for each subband set in a higher layer. layer configured sub-band feedback).
- the RI may indicate information on the number of layers recommended by the terminal. That is, RI may represent the number of streams used for spatial multiplexing. The RI may be fed back only when the terminal operates in the MIMO mode using spatial multiplexing. For example, RI is not fed back in single antenna port mode or transmit diversity mode.
- the RI is always associated with one or more CQI feedback.
- the fed back CQI is calculated assuming a specific RI value. Since the rank of the channel generally changes slower than the CQI, the RI can be fed back less than the CQI.
- the transmission period of the RI may be a multiple of the CQI / PMI transmission period. RI is given for the entire system band and frequency selective RI feedback is not supported.
- the scheme of transmitting uplink control information includes periodic transmission and aperiodic transmission. Periodic transmission is usually transmitted on the PUCCH, but may be transmitted on the PUSCH. Aperiodic transmission is performed by requesting the terminal when the base station needs more accurate channel state information. Aperiodic transmission is performed on the PUSCH. The use of PUSCH allows for greater capacity and detailed channel state reporting. If the periodic transmission and the aperiodic transmission collide, only the aperiodic transmission is transmitted.
- a different CQI feedback method may be applied according to the characteristics of the communication scheme. For example, in the CoMP JT method or the single-cell SU-MIMO method, since the signal from the cell (s) is transmitted to one terminal, the difference between the channel information measured and fed back by the terminal and the channel quality actually transmitted. May not be large. On the other hand, in the CoMP CBF scheme or single-cell MU-MIMO scheme, signals from cell (s) are transmitted to a plurality of terminals, and the channel quality measured by one terminal may be affected by a channel to another terminal.
- a difference may occur between the channel information that the UE measures and feeds back the channel quality and the channel quality actually transmitted.
- the base station determines the MCS of the transmission signal based on the fed back CQI, a new method of feeding back the channel quality correction information back to the cell (s) may be considered in consideration of the channel quality when the signal is actually transmitted. .
- a method in which the UE informs the cell of the CQI correction information for the single-cell MU-MIMO may be considered. Specifically, it is assumed that when a terminal feeds back a CQI in a single-cell SU-MIMO to a cell, it operates in a single-cell MU-MIMO scheme by pairing with another terminal using specific precoding information. Thus, correction information indicating how the CQI in MU-MIMO (that is, considering another terminal) is changed compared to the CQI in SU-MIMO may be fed back together.
- the terminal may provide the CQI in the CoMP CBF scheme or the single-cell MU-MIMO scheme to the cell (s) as correction information based on the CQI in the CoMP JT scheme or the single-cell SU-MIMO scheme. have.
- the existing CQI calculation and transmission method (ie, the first hypothesis of CQI calculation) can be applied to the CoMP JT method and the single-cell SU-MIMO method, and the CoMP CBF method and the single-cell MU are applied.
- a new CQI calculation and transmission method (ie, a second hypothesis of CQI calculation) may be applied.
- the UE transmits the CQI and / or RI based on the same hypothesis about the above considerations for the CQI and / or RI transmission for the CoMP communication scheme and the single-cell MIMO communication scheme that are interoperated with each other. And dynamic switching between the single-cell MIMO communication scheme can be easily performed.
- the multi-cell channel information feedback for CoMP operation is composed of a combination of channel information feedback for individual cooperative cells.
- the UE performing the feedback for the CoMP operation may use each CoMP cooperative cell using a feedback codebook of a single-cell MIMO communication method (interlocked) corresponding to the corresponding CoMP communication method that is semi-statically configured.
- the channel information of may be fed back.
- a feedback codebook optimized for high rank may be used for the CoMP JT scheme and the single-cell SU-MIMO scheme.
- a codebook composed of a unitary matrix column of the matrix has orthogonality
- the terminal may assume that the base station classifies different layers using a precoding vector having orthogonality.
- a feedback codebook defined in 3GPP LTE Release-8 or an extended codebook thereof may be used.
- feedback may be performed on the serving cell based on the codebook-based transmission precoding hypothesis (the hypothesis to use LTE Release-8 codebook or its extended codebook).
- the codebook-based transmission precoding hypothesis the hypothesis to use LTE Release-8 codebook or its extended codebook.
- a transmission precoding hypothesis for the serving cell and the cooperating cell (s), and a transmit PMI (TPMI) are used while using the feedback codebook or the extended codebook used in the SU-MIMO scheme.
- the feedback may be performed based on the relative phase information between the).
- a feedback codebook optimized for low rank may be used.
- the codebook is composed of unitary matrices.
- the codebook can be configured with a non-unitary matrix, the codebook can be designed to deliver more accurate channel information.
- the terminal may not assume that the base station distinguishes different layers using a precoding vector having orthogonality.
- feedback may be performed based on a quantized channel or a quantized effective channel with respect to a serving cell, and thus a reception process may be reflected.
- feedback may be performed based on a quantized channel or a quantized effective channel for the serving cell and the cooperative cell (s).
- the feedback codebook when the feedback codebook is represented in the form of a matrix, it may include a non-unitary matrix.
- the feedback codebook when the feedback codebook is represented by a column vector, the vectors do not need to have mutual orthogonality. Can be configured.
- CoMP CBF scheme and single-cell MU-MIMO scheme feedback with higher granularity than feedback codebook used for CoMP JT scheme and single-cell SU-MIMO scheme for more accurate channel information delivery.
- Codebooks are available. For example, increasing the size of the feedback codebook (i.e., feeding back channel status using more bits), or applying techniques such as hierarchical codebook or adaptive codebook. can do.
- Hierarchical codebook technology means that the feedback accuracy is improved by using different feedback codebooks (including multiple resolution codebooks with different resolutions) at each feedback time point, and adaptive codebook technology is applied to a given basic feedback codebook. This means using a feedback codebook obtained through a modification such as multiplying a long-term channel covariance matrix.
- Codebook extensibility basically means that a subset of codebooks used in one of the different communication schemes may constitute a codebook of another communication scheme, while using the same codebook between different communication schemes. For example, while defining and using the same codebook as the single-cell MIMO communication method and the CoMP communication method, the codebook in the single-cell MIMO communication method may be set to a subset of the codebooks used in the CoMP communication method.
- codebook scalability is basically applied between interworking CoMP communication schemes and single-cell MIMO communication schemes to facilitate dynamic switching between them.
- the precoding codebook reuses the single-cell SU-MIMO precoding codebook (for example, the codebook defined in LTE Release-8) to precode the antenna port of each cell. This can be applied.
- the CoMP JP scheme may apply potentially different phase adjustment values for each cell.
- the precoding codebook in the single-cell MU-MIMO scheme and the feedback codebook in the CoMP CBF scheme may be scalable.
- the single-cell MU-MIMO feedback codebook and the CoMP CBF feedback codebook may be the same codebook, or the single-cell MU-MIMO precoding codebook may be a subset of the CoMP CBF feedback codebook.
- the feedback codebook used in the CoMP CBF scheme may be a codebook composed of a non-unitary matrix.
- the CoMP CBF scheme when a plurality of vectors are fed back by a terminal (for example, feedback for a high rank or feedback for both serving cell and cooperative cell (s)), the plurality of vectors are mutually orthogonal. You don't have to have it.
- the precoding codebook in the single-cell SU-MIMO scheme and the feedback codebook in the CoMP CBF scheme may have scalability. That is, the single-cell SU-MIMO precoding codebook may be a subset of the CoMP CBF feedback codebook. Specifically, the CoMP CBF feedback codebook may be a codebook composed of non-unitary matrices, but the single-cell SU-MIMO precoding codebook may be composed of a subset consisting of only unitary matrices in the CoMP CBF feedback codebook.
- the single-cell MU-MIMO feedback codebook and the single-cell SU-MIMO precoding codebook may each be composed of a subset of the CoMP CBF feedback codebook, and furthermore, the single-cell MU-MIMO feedback codebook and the single-cell MU-MIMO feedback codebook.
- the cell SU-MIMO precoding codebook may consist of the same codebook.
- the feedback codebook is dynamically configured between different communication schemes. It can be said.
- a terminal operating according to a single-cell MIMO communication method transmits feedback information to only one cell, but a terminal operating according to CoMP communication method is required to transmit feedback information to a plurality of cells.
- the feedback in the CoMP communication method may be configured as an extension of the feedback in the single-cell MIMO communication method.
- the feedback mode thereof may consider feedback for the high rank transmission.
- the low rank transmission is generally performed in the single-cell MU-MIMO scheme and the CoMP CBF scheme, the feedback mode thereof may consider the feedback for the low rank transmission.
- the feedback mode may be scalable or may have a common feedback mode.
- the single-cell SU-MIMO scheme and the CoMP JP scheme may have an expandable feedback relationship. That is, the feedback information in the single-cell SU-MIMO scheme may be a subset of the feedback information in the CoMP JP scheme.
- the single-cell SU-MIMO scheme and the CoMP JP scheme may have a common feedback mode. That is, the single-cell SU-MIMO scheme may be treated as a special case of the CoMP JP scheme in which the CoMP set size (SET SIZE) is one. CoMP set size information may be known to the terminal by the base station.
- SET SIZE CoMP set size
- the single-cell MU-MIMO scheme and the CoMP CBF scheme may have a scalable feedback relationship. That is, the feedback information in the single-cell MU-MIMO scheme may be a subset of the feedback information in the CoMP CBF scheme.
- the single-cell MU-MIMO scheme and the CoMP CBF scheme may have a common feedback mode. That is, the single-cell MU-MIMO scheme may be treated as a special case of the CoMP CBF scheme where the CoMP set size is 1 (SET SIZE). CoMP set size information may be known to the terminal by the base station.
- semi-static feedback mode switching may be applied between the CoMP communication method and the single-cell MIMO communication method that are not interoperable. That is, feedback mode switching between one of the single-cell SU-MIMO scheme or the CoMP JP scheme and one of the single-cell MU-MIMO scheme or the CoMP CBF scheme may be performed semi-statically.
- various MIMO transmission modes may be used in some cases.
- the MIMO transmission mode may be indicated through scheduling signaling (PDCCH DCI format), and various DCI formats according to various MIMO transmission modes may be used.
- PDCCH DCI format scheduling signaling
- different DCI formats may be used to indicate when different MIMO transmission modes are used according to various communication schemes.
- dynamic transmission mode switching is performed between an interworking CoMP communication scheme and a single-cell MIMO communication scheme. That is, the transmission mode may be switched between the CoMP communication method and the single-cell MIMO communication method that are interoperable without additional signaling.
- dynamic transmission mode switching may be applied between the single-cell SU-MIMO scheme and the CoMP JP scheme.
- a single transmission mode may be applied between the single-cell SU-MIMO scheme and the CoMP JP scheme.
- dynamic transmission mode switching may be applied between the single-cell MU-MIMO scheme and the CoMP CBF scheme, or a single transmission mode may be applied (ie, transparent).
- the transmission mode switching between one of the single-cell SU-MIMO scheme or the CoMP JP scheme and one of the single-cell MU-MIMO scheme or the CoMP CBF scheme may be performed semi-statically.
- a dynamic transmission mode switching is applied between a single-cell SU-MIMO scheme, a CoMP JP scheme, a single-cell MU-MIMO scheme, and a CoMP CBF scheme, or a single transmission mode is applied. (I.e., transparent).
- DRS dedicated reference signal
- FIG. 11 is a flowchart illustrating a dynamic switching method between a CoMP communication mode and a single-cell MIMO communication mode according to an embodiment of the present invention.
- the terminal may operate according to the first communication mode.
- the first communication mode may be one of a CoMP communication mode or a single-cell MIMO communication mode.
- the terminal may generate and transmit channel feedback information to the cell (s).
- the first feedback codebook may be used.
- the terminal may perform switching from the first communication mode to the second communication mode.
- the second communication mode is a communication mode interworking with the first communication mode, and when the first communication mode is one of a CoMP communication mode or a single-cell MIMO communication mode, the second communication mode may be determined as the other communication mode among them. Can be. That is, when the first communication mode is the CoMP communication mode, the second communication mode may be a single-cell MIMO communication mode linked to the corresponding CoMP communication mode. Alternatively, when the first communication mode is a single-cell MIMO communication mode, the second communication mode may be a CoMP communication mode linked to the corresponding single-cell MIMO communication mode. Since the first communication mode and the second communication mode are linked to each other, the terminal may perform communication mode switching without additional signaling from the base station. This may be referred to as dynamic switching of the communication mode as described above.
- the interworking of the first communication mode and the second communication mode may be set between a CoMP communication method supporting high rank transmission and a single-cell MIMO communication method supporting high rank transmission. That is, interworking of the first and second communication modes may be set between the CoMP JT scheme and the single-cell SU-MIMO scheme. Alternatively, the interworking of the first communication mode and the second communication mode may be set between a CoMP communication method supporting low rank transmission and a single-cell MIMO communication method supporting low rank transmission. That is, interworking of the first and second communication modes may be established between the CoMP CBF scheme and the single-cell MU-MIMO scheme.
- the terminal may operate according to the second communication mode.
- the terminal may generate and transmit channel feedback information to the cell (s).
- a second feedback codebook may be used.
- the first feedback codebook and the second feedback codebook may be the same feedback codebook.
- one of the first feedback codebook and the second feedback codebook may be configured as a subset of the other.
- the second feedback codebook may be configured as a subset of the first feedback codebook (or the first communication mode).
- the first feedback codebook may consist of a subset of the second feedback codebook).
- the feedback information in the single-cell MIMO communication mode may consist of a subset of the feedback information in the CoMP communication mode.
- the first feedback codebook and the second feedback codebook may be configured as a unitary matrix.
- the first feedback codebook and the second feedback codebook may be configured with a non-unitary matrix.
- the feedback codebook used in the CoMP CBF scheme and the single-cell MU-MIMO scheme may be a feedback codebook having higher granularity than the feedback codebook used between the CoMP JT scheme and the single-cell SU-MIMO scheme. have.
- the feedback codebook with higher precision may be composed of a feedback codebook of a larger size, or may be configured using the hierarchical codebook or the adaptive codebook technique described above.
- first feedback information and the second feedback information may include CQI and / or RI information, and the CQI and / or RI information may be interlocked with the first communication mode and the second communication mode (ie, interworking single- Cell MIMO communication mode and CoMP communication mode).
- the same MIMO transmission scheme may be used in the interworking first communication mode and the second communication mode (that is, the interworking single-cell MIMO communication mode and the CoMP communication mode).
- FIG. 12 is a diagram showing the configuration of a preferred embodiment of a terminal device according to the present invention.
- the terminal 1210 may include a receiving module 1211, a transmitting module 1212, a processor 1213, a memory 1214, and a plurality of antennas 1215.
- the plurality of antennas refers to a terminal that supports a multiple input multiple output (MIMO) technique.
- the terminal 1210 may perform multi-cell communication with the plurality of base stations 1221 and 1222.
- the receiving module 1211 may receive various signals, data, and information on downlink from the base station.
- the transmission module 1212 may transmit various signals, data, and information on the uplink to the base station.
- the processor 1213 may control operations of the entire terminal 1210. In particular, the processor 1213 may control transmission and reception of various signals, data, and information through the reception module 1211 and the transmission module 1212.
- the terminal 1210 may perform an operation of dynamically switching the communication mode.
- the processor 1213 of the terminal device 1210 may generate first feedback information according to the first communication mode, generate second feedback information according to the second communication mode, and transmit a transmission module.
- the first feedback information may be transmitted when operating in the first communication mode
- the second feedback information may be transmitted when operating in the second communication mode.
- the processor 1213 may be configured to perform switching between the first communication mode and the second communication mode.
- the first communication mode and the second communication mode are interworking communication modes
- the first communication mode is one of a multi-cell cooperative multipoint (CoMP) communication mode or a single-cell multiple input / output (MIMO) communication mode.
- the two communication modes may be one of the other communication modes.
- the processor 1213 may perform switching between the first communication mode and the second communication mode without signaling from the base station.
- CoMP multi-cell cooperative multipoint
- MIMO single-cell multiple input / output
- the processor 1213 of the terminal device 1210 performs a function of processing the information received by the terminal, information to be transmitted to the outside, and the like, and the memory 1214 may store the processed information and the like for a predetermined time. It may be replaced by a component such as a buffer (not shown).
- Embodiments of the present invention described above may be implemented through various means.
- embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.
- a method according to embodiments of the present invention may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), and Programmable Logic Devices (PLDs). It may be implemented by field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.
- ASICs Application Specific Integrated Circuits
- DSPs Digital Signal Processors
- DSPDs Digital Signal Processing Devices
- PLDs Programmable Logic Devices
- FPGAs field programmable gate arrays
- processors controllers, microcontrollers, microprocessors, and the like.
- the method according to the embodiments of the present invention may be implemented in the form of a module, procedure, or function that performs the functions or operations described above.
- the software code may be stored in a memory unit and driven by a processor.
- the memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.
- Embodiments of the present invention as described above may be applied to various mobile communication systems.
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Abstract
Description
Claims (14)
- 통신 모드를 동적으로 스위칭하는 방법으로서,제 1 통신 모드에 따라 제 1 피드백 정보를 생성 및 전송하는 단계;상기 제 1 통신 모드에서 상기 제 1 통신 모드와 연동되는 제 2 통신 모드로 스위칭하는 단계; 및상기 제 2 통신 모드에 따라 제 2 피드백 정보를 생성 및 전송하는 단계를 포함하고,상기 제 1 통신 모드는 다중-셀 협력멀티포인트(CoMP) 통신 모드 또는 단일-셀 다중입출력(MIMO) 통신 모드 중 하나이고, 상기 제 2 통신 모드는 상기 CoMP 통신 모드 또는 상기 단일-셀 MIMO 모드 중 상기 제 1 통신 모드 이외의 나머지 하나이며,상기 스위칭 단계는 기지국으로부터의 시그널링에 의하지 않고 수행되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 통신 모드와 상기 제 2 통신 모드의 연동은,높은 랭크 전송을 지원하는 CoMP 통신 방식과 높은 랭크 전송을 지원하는 단일-셀 MIMO 통신 방식 사이에서 설정되고,낮은 랭크 전송을 지원하는 CoMP 통신 방식과 낮은 랭크 전송을 지원하는 단일-셀 MIMO 통신 방식 사이에서 설정되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 높은 랭크 전송을 지원하는 CoMP 통신 방식과 상기 높은 랭크 전송을 지원하는 단일-셀 MIMO 통신 방식은, 각각 CoMP JT(Joint Transmission) 방식과 단일-셀 단일사용자-MIMO(SU-MIMO) 방식이고,상기 낮은 랭크 전송을 지원하는 CoMP 통신 방식과 상기 낮은 랭크 전송을 지원하는 단일-셀 MIMO 통신 방식은, 각각 CoMP CBF(Coordinated BeamForming) 방식과 단일-셀 다중사용자-MIMO(MU-MIMO) 방식인, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 피드백 정보 및 상기 제 2 피드백 정보는,동일한 피드백 코드북을 사용하여 생성되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 피드백 정보는 제 1 피드백 코드북을 사용하여 생성되고,상기 제 2 피드백 정보는 제 2 피드백 코드북을 사용하여 생성되며,상기 제 1 피드백 코드북 및 상기 제 2 피드백 코드북 중 하나는 나머지 하나의 부분집합으로 구성되는, 통신 모드의 동적 스위칭 방법.
- 제 5 항에 있어서,상기 CoMP 통신 모드에서 사용되는 피드백 코드북의 부분집합으로 상기 단일-셀 MIMO 통신 모드에서 사용되는 피드백 코드북이 구성되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 단일-셀 MIMO 통신 모드에서의 피드백 정보는 상기 CoMP 통신 모드에서의 피드백 정보의 부분집합인, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 통신 모드 및 상기 제 2 통신 모드의 연동이 CoMP JT 방식 및 단일-셀 SU-MIMO 방식 사이에서 설정되는 경우,상기 제 1 피드백 정보 및 상기 제 2 피드백 정보는, 유니터리 행렬로 구성된 피드백 코드북을 사용하여 생성되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 통신 모드 및 상기 제 2 통신 모드의 연동이 CoMP CBF 방식 및 단일-셀 MU-MIMO 방식 사이에서 설정되는 경우,상기 제 1 피드백 정보 및 상기 제 2 피드백 정보는, 비-유니터리 행렬로 구성된 피드백 코드북을 사용하여 생성되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 피드백 정보 및 상기 제 2 피드백 정보는,상기 제 1 통신 모드 및 상기 제 2 통신 모드의 연동이 CoMP CBF 방식 및 단일-셀 MU-MIMO 방식 사이에서 설정되는 경우에, 상기 제 1 통신 모드 및 상기 제 2 통신 모드의 연동이 CoMP JT 방식 및 단일-셀 SU-MIMO 방식 사이에서 설정되는 경우에 비하여, 보다 높은 정밀도(granularity)를 가지는 피드백 코드북을 사용하여 생성되는, 통신 모드의 동적 스위칭 방법.
- 제 10 항에 있어서,상기 보다 높은 정밀도를 가지는 피드백 코드북은,보다 큰 크기의 피드백 코드북, 계층적 코드북, 또는 적응적 코드북으로 구성되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 피드백 정보 및 상기 제 2 피드백 정보는,채널품질지시자(CQI) 계산에 대한 동일한 가설에 기초하여 생성되는, 통신 모드의 동적 스위칭 방법.
- 제 1 항에 있어서,상기 제 1 통신 모드 및 상기 제 2 통신 모드에서 동일한 MIMO 전송 기법이 사용되는, 통신 모드의 동적 스위칭 방법.
- 통신 모드를 동적으로 스위칭하는 단말로서,기지국으로부터 하향링크 신호를 수신하는 수신 모듈;상기 기지국으로 상향링크 신호를 전송하는 전송 모듈; 및상기 수신 모듈 및 상기 전송 모듈을 포함하는 상기 단말을 제어하는 프로세서를 포함하고,상기 프로세서는,제 1 통신 모드에 따라 제 1 피드백 정보를 생성하고, 제 2 통신 모드에 따라 제 2 피드백 정보를 생성하고,상기 전송 모듈을 통하여, 상기 제 1 통신 모드에서 동작하는 경우 상기 제 1 피드백 정보를 전송하고 상기 제 2 통신 모드에서 동작하는 경우 상기 제 2 피드백 정보를 전송하고,상기 제 1 통신 모드와 상기 제 2 통신 모드 간에 스위칭을 수행하도록 구성되며,상기 제 1 통신 모드와 상기 제 2 통신 모드는 연동되는 통신 모드이고,상기 제 1 통신 모드는 다중-셀 협력멀티포인트(CoMP) 통신 모드 또는 단일-셀 다중입출력(MIMO) 통신 모드 중 하나이고, 상기 제 2 통신 모드는 상기 CoMP 통신 모드 또는 상기 단일-셀 MIMO 모드 중 상기 제 1 통신 모드 이외의 나머지 하나이며,상기 제 1 통신 모드와 상기 제 2 통신 모드 간의 스위칭은 상기 기지국으로부터의 시그널링에 의하지 않고 수행되는, 통신 모드 동적 스위칭 단말.
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EP10823556.5A EP2490345B1 (en) | 2009-10-14 | 2010-10-05 | Method and apparatus for mode switching between a multi-cell coordinated communication mode and a single-cell mimo communication mode |
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KR100964438B1 (ko) * | 2008-12-19 | 2010-06-16 | 성균관대학교산학협력단 | 효과적인 다중 셀 간섭 제어 서비스 방법 및 그 장치 |
US20110009105A1 (en) * | 2009-07-13 | 2011-01-13 | Jungwoo Lee | Self-organizing networks using directional beam antennas |
US8687602B2 (en) * | 2009-09-29 | 2014-04-01 | Apple Inc. | Methods and apparatus for error correction for coordinated wireless base stations |
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2010
- 2010-10-05 US US13/497,248 patent/US8665817B2/en not_active Expired - Fee Related
- 2010-10-05 KR KR1020127006375A patent/KR101753589B1/ko active IP Right Grant
- 2010-10-05 EP EP10823556.5A patent/EP2490345B1/en not_active Not-in-force
- 2010-10-05 WO PCT/KR2010/006792 patent/WO2011046317A2/ko active Application Filing
Non-Patent Citations (2)
Title |
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None |
See also references of EP2490345A4 |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2702778A1 (en) * | 2011-04-29 | 2014-03-05 | NEC Laboratories America, Inc. | Enhancement of download multi-user multiple-input multiple-output wireless communications |
EP2702778A4 (en) * | 2011-04-29 | 2014-10-08 | Nec Lab America Inc | DOWNLOAD REINFORCEMENT FOR WIRELESS MIMO COMMUNICATION WITH SEVERAL USERS |
US9532257B2 (en) | 2011-04-29 | 2016-12-27 | Nec Corporation | Enhancement of download multi-user multiple-input multiple-output wireless communications |
Also Published As
Publication number | Publication date |
---|---|
EP2490345B1 (en) | 2019-04-17 |
EP2490345A4 (en) | 2017-03-29 |
KR20120112370A (ko) | 2012-10-11 |
WO2011046317A3 (ko) | 2011-09-09 |
US20120189077A1 (en) | 2012-07-26 |
KR101753589B1 (ko) | 2017-07-04 |
EP2490345A2 (en) | 2012-08-22 |
US8665817B2 (en) | 2014-03-04 |
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